On DZone.com's PHP on Windows section today Krzysztof Kotowicz has a new post talking about a file path injection exploit in PHP versions lower than 5.3.6.

Since the thing went public before new PHP version has been released, I present full details of the latest PHP vulnerability I reported - together with some sweet demo exploit. The issue was found with fuzzing being part of my recent file upload research. And I still have some more to show in the future :)

The issue, described in more detail here on bugs.php.net (as of the time of this post, unfortunately unavailable) and his code to reproduce the issue is here. Due to a bug in the code that should strip down the upload to just the filename, certain kinds of file paths can make it through. The real problem comes in when an application blindly uses this filename to write to, possibly overwriting important files. You can see a screenshot of it in action here.